Magnus force and acoustic Stewart-Tolman effect in type II superconductors

TL;DR

This paper introduces a novel method to measure the effective Magnus force in type II superconductors using the acoustic Stewart-Tolman effect, revealing how the gyroscopic force varies across different materials and states.

Contribution

It presents a new measurement technique for the Magnus force in superconductors that does not require flux flow, enabling studies across most of the mixed state.

Findings

In borocarbides, the gyroscopic force sign remains the same in the mixed and normal states.

In Nb, the gyroscopic force changes sign during the transition from normal to mixed state.

The method allows investigation of the gyroscopic force without flux flow conditions.

Abstract

At zero magnetic field we have observed an electromagnetic radiation from superconductors subjected by a transverse elastic wave. This radiation has an inertial origin, and is a manifestation of the acoustic Stewart-Tolman effect. The effect is used for implementing a method of measurement of an effective Magnus force in type II superconductors. The method does not require the flux flow regime and allows to investigate this force for almost the whole range of the existence of the mixed state. We have studied behavior of the gyroscopic force in nonmagnetic borocarbides and Nb. It is found that in borocarbides the sign of the gyroscopic force in the mixed state is the same as in the normal state, and its value (counted for one vortex of unit length) has only a weak dependence on the magnetic field. In Nb the change of sign of the gyroscopic force under the transition from the normal to the mixed state is observed.